Controlled voltage power supply circuits can commonly be regulated but, regulation arrangements in variable power supply circuits are typically not able to provide adequate protection against over-current or short circuit conditions. One such circuit protection problem relates to fan start-up conditions that impact variable power supply requirements. The current drawn by fans at their start-up can be much greater than the normal current drawn for operating. Moreover, for those types of fans that are hot-swappable or are connected with cables, protection for a situation of over-current is required for both safety as well as equipment protection reasons.